Six-Month Local Control Rates and Immune Responses After Pulsed Electric Field Ablation in Metastatic Cancer.

Background: The AFFINITY trial (NCT05890872) is a prospective, non-randomized, open-label, single-arm study evaluating the safety, immunological impact, and preliminary efficacy of Aliya pulsed electric field ablation in patients with solid tumors. Thirty-one patients were enrolled; thirty received lung lesion ablation prior to continuation on standard-of-care treatment. This manuscript reports six-month local control outcomes and immunological response characteristics. Radiological outcomes were assessed using a modified RECIST 1.1, and immunological impact was evaluated via changes in peripheral blood immunocyte populations and detection of immunoglobulins (Ig) to tumor-associated antigens in serum post-ablation. Methods: Twenty-eight patients underwent radiological assessment of ablated lesions at approximately 1-, 3-, and 6-month post-ablation to evaluate local control. Peripheral blood was collected for immune monitoring using flow cytometry and to detect IgG responses to biopsy-specific and tumor-associated antigens. Results: At 6 months, two cohorts emerged: 12 received ablation only, and 16 received ablation plus systemic and/or focal therapies (radiotherapy or second ablation). In the ablation-only group, imaging showed local control in all ablated lesions (8/12 SD, 4/12 PR), suggesting local efficacy without systemic therapy in those patients. Immunophenotyping showed dynamic changes in circulating immune cells, including T and B cell activation. A subset also exhibited modulation of tumor antigen-specific IgG, indicating a systemic humoral response. Conclusions: This analysis provides preliminary evidence that this form of ablation may promote local tumor control and modulate systemic immune function. These findings support the immunogenic potential of this specialized energy and warrant further investigation. Extended 12-month data for the full cohort will be reported in a future manuscript.